Messages in this thread | | | Date | Sat, 19 Jul 2008 03:30:50 +0200 | From | Pierre Ossman <> | Subject | Re: linux-next: Tree for July 16 (crash on quad core AMD) |
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On Sat, 19 Jul 2008 09:59:11 +0900 Tejun Heo <htejun@gmail.com> wrote:
> Pierre Ossman wrote: > > I just have one objection to your version, and that is that it cannot > > be used to nibble away at the sg list. The _next() call jumps an entire > > page, whereas you sometimes need to consume that page in two different > > sweeps. This could be handled by some external buffer that keeps the > > remainder of the page, but the point of these functions was to keep > > things simple for the callers. > > Well, I don't know how often such usages would be necessary. If it's a > very common ops, you can add a param to the next function but frankly I > think it's better to build a inside control structure for that. There's > no need for external buffer, just an inner loop is sufficient. >
I'm not sure how this can be solved by an inner loop. My primary use case is:
1. Wait for interrupt 2. Write n bytes 3. goto 1
n has no guarantee of being aligned to any page boundaries, so state needs to be kept between each invokation of writing a chunk of data. I doubt I'm alone in this use pattern (in fact, most device drivers using PIO should do something similar).
-- -- Pierre Ossman
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